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Here’s a clever idea from Harry if you’re willing to play the long game in tracking down redundant CSS—add a transparent background image to the rule block and then sit back and watch your server logs for any sign of that sleeper agent ever getting activated.

If you do find entries for that particular image, you know that, somehow, the legacy feature is potentially still accessible—the number of entries should give you a clue as to how severe the problem might be.

Just like many people develop with an average connection speed in mind, many people have a fixed view of who a user is. Maybe they think there are customers with a lot of money with fast connections and customers who won’t spend money on slow connections. That is, very roughly speaking, perhaps true on average, but sites don’t operate on average, they operate in particular domains.

A comprehensive overview of rel="preload" which looks very useful indeed …I just wish it wasn’t (like “nofollow”) a nonsensical value for the rel attribute: a resource can’t have a relationship of “preload” to the linking document.

Google has updated its advice to people making websites, who might want to have those sites indexed by Google. There are two simple bits of advice: optimise for performance, and use progressive enhancement.

Just like modern browsers, our rendering engine might not support all of the technologies a page uses. Make sure your web design adheres to the principles of progressive enhancement as this helps our systems (and a wider range of browsers) see usable content and basic functionality when certain web design features are not yet supported.

This looks like a really handy tool for reducing the file size of JPEGs without any perceptible loss of quality (in much the same way that ImageOptim works for PNGs)—available as a Mac app or an installable web service.